Fetal RHD genotyping after bone marrow transplantation.

Background: Fetal RHD genotyping allows targeted diagnostic testing, fetal surveillance, and eventually intrauterine treatment to D-alloimmunized pregnant women who carry an RHD+ fetus. However, false-positive and false-negative results of noninvasive prenatal fetal RHD genotyping have been described due to a variety of causes. In this case report we present two cases where noninvasive fetal RHD typing was complicated by a previous bone marrow transplantation (BMT).

Frequency and characterization of known and novel RHD variant alleles in 37 782 Dutch D-negative pregnant women.

To guide anti-D prophylaxis, Dutch D- pregnant women are offered a quantitative fetal-RHD-genotyping assay to determine the RHD status of their fetus. This allowed us to determine the frequency of different maternal RHD variants in 37 782 serologically D- pregnant women. A variant allele is present in at least 0·96% of Dutch D- pregnant women The D- serology could be confirmed after further serological testing in only 54% of these women, which emphasizes the potential relevance of genotyping of blood donors.

Analysis of false-positive results of fetal RHD typing in a national screening program reveals vanishing twins as potential cause for discrepancy.

Objectives: We aim to elucidate causes of false-positive fetal RHD screening results obtained with cell-free DNA.

Methods: Fetal RHD screening was performed in 32,222 samples from RhD-negative women by multiplex real-time PCR in triplicate for RHD exons 5 and 7 using cell-free DNA isolated from maternal plasma obtained in the 27th gestational week. PCR results were compared with cord blood serology in 25,789 pregnancies (80.

Reliability of fetal sex determination using maternal plasma.

Objective: To determine the diagnostic accuracy of noninvasive fetal sex determination in maternal plasma.

Methods: All consecutive patients for whom fetal sex determination in maternal plasma was performed in our laboratory from 2003 up to 2009 were included in the study. Real-time polymerase chain reaction was performed for the SRY gene and multicopy DYS14 marker sequence.

Use of bi-allelic insertion/deletion polymorphisms as a positive control for fetal genotyping in maternal blood: first clinical experience.

Amplification of fetal DNA in maternal plasma is a new way for non-invasive fetal genotyping in pregnancies at risk for disorders where the presence of a paternal DNA sequence contributes to the risk status of the fetus. We describe the use of a panel of 10 bi-allelic highly polymorphic markers to ascertain the presence and amplification of fetal DNA in case the fetus is negative for the targeted paternal "disease" sequence.